The present invention relates generally to microscope slides for cytological analysis, and more particularly, to an improved slide which ensures that all of the cells present in the smear to be analyzed will be screened.
The standard procedure for the early detection of uterine cancer is the "Pap test." This test was named after Dr. George N. Papanicolaou who discovered that there were certain pathologic cells correlated with uterine cancer and these cells could be dectected when the cancer was at an early stage by examining through a microscope a slide on which a vaginal smear or preferably cervical scrapings had been placed and stained.
In carrying out the "Pap test" a conventional glass microscope slide is prepared with a smear made up of scrapings and secretion from the cervical area utilizing any one of the methods well known and universally accepted by the medical profession.
The smear on the prepared slide is then viewed through a microscope by a trained individual such as a cytologist who endeavors to view the entire smear covered by the cover slip on the slide to determine if any cancer cells are present in the smear. Inasmuch as the number of malignant cells which are exfoliated greatly increases as the uterine cancer enters advance stages, the early stages of the cancer where detection is important requires extremely accurate viewing of the slide since there could be only one or several malignant cells present in the entire smear.
The procedure conventionally utilized to view "Pap smears" to detect the presence of any malignant cells is for the viewer to start at one outer boundary of the smear under the cover slip of the slide and by operating the stage of the microscope, make a plurality of successive parallel passes either lengthwise or widthwise with respect to the slide, with each successive pass encompassing the adjacent field of view as best determined by the viewer with the field of view being dependent on the power of the lens and eyepiece of the microscope.
While the above procedure is generally satisfactory, there are several inherent factors which affect accuracy which in turn could result in a lone cancer cell being undetected. This would be at a time when the patient's cancer is at a very early stage and the rate of cure is very high.
The major factor affecting accuracy in the above procedure is the dependency on the eye of the viewer to judge when the stage of the microscope has been advanced so that the next pass will cover the field of view adjacent to that which has just been viewed. Although an insufficient movement will not affect accuracy since an overlapping will take place and a portion of the field viewed in the previous pass will be re-viewed, and excessive overlap will greatly increase the time required to screen a slide and will hasten the fatigue of the viewer. If an excessive movement is made, there may be a narrow strip between the successive passes that is not viewed in which a malignant cell could conceivably be located.
In addition to loss of accuracy by the user depending on his eye for guidance to the adjacent field of view, the slide could possibly be slightly dislodged during viewing or one of the knobs on the microscope stage accidently moved, either of which possibly resulting in a critical area of the smear remaining unviewed.